Calcaneum translation plate

ABSTRACT

A calcaneum translation plate ( 1 ) characterised in that it comprises two end portions, i.e. a proximal anchoring portion ( 2 ) and a distal fixing portion ( 3 ), oriented in opposing directions and arranged in spaced parallel planes (P-P, P′-P′), said proximal and distal portions connecting to an intermediate portion ( 4 ) having a square general profile and comprising two perpendicular bearing surfaces, the proximal anchoring portion extending from one ( 5 ) of said surfaces and perpendicular thereto, whereas the distal fixing portion extends in the extension of the other bearing surface ( 6 ).

CROSS-REFERENCE TO RELATED U.S. APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

REFERENCE TO AN APPENDIX SUBMITTED ON COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of corrective orthopedicsurgery.

It concerns an implant intended for osteotomy operations. Moreprecisely, the invention is relative to a calcanean translation plate.

2. Description of Related Art Including Information Disclosed Under 37CFR 1.97 and 37 CFR 1.98.

The skeletal bones of human beings and vertebrates generally consist ofat least two areas: a rigid cortical area and an internal spongy area ofmore tender consistency which may itself, for certain bones, betraversed by a marrowy canal enclosing soft tissues.

The human hindfoot is essentially comprised of two bones: the ankle-bone(or astragalus) above which is placed on the calcaneum below. Thecalcaneum is a short bone, even and asymmetric, of elongated shape fromthe rear end forward and flattened across. The association of thecalcaneum and the ankle-bone forms the heel on which rests most of thebody's weight. This part of the foot is therefore subject to heavypressures which makes it prone to various malformations, sources of painand difficulty and/or incapability of walking for the patients.

It is sometimes indispensable to correct the shape of the calcaneum. Theintervention consists of an osteotomy of said bone with medialization ofthe large tuberosity, i.e. the section of the calcaneum into two partsand the displacement of one in relation to the other. This will allow abetter support of the hindfoot and above all reducing the internalconstraints on the muscles and ligaments.

Osteotomy designates the surgical section of a long bone in order tomodify its axis, size or shape for therapeutic or plastic purposes; itis directed at restituting better axes to long bones in order to betterdistribute the pressures on the corresponding articulations. Then, theprinciple is either to cut out a slice over the width of the bone, andto refasten the remaining pieces after having removed it, or to simplycut across and to open the space of one side, by filling the voidcreated with a bone graft, depending on whether one wants to close anangle or open it. Osteotomy may also be followed by a translation, i.e.the shifting of one of the parts of the bone resulting from thissection.

This operation requires the installation of support systems for thecalcaneum in order to keep the translation in place. As far as thecalcaneum is concerned, this part of the foot being subjected to verystrong pressures due to the weight of the body and its role in walking,the major difficulty is to produce orthopedic systems that aresufficiently stable and rigid to remain in place and maintain thetranslation of the calcaneum.

One knows of calcanean implants of diverse and varied shapes, but theperpetuation of the system, i.e. its lasting stability and rigidity, isoften uncertain because the implant rests generally in the spongy partof the calcaneum, in spite of the locally harder thalamic crossings,which leads to a rotation of the system as well as a slipping of thelatter under the effect of the forces of the body's weight and theporosity of the spongy part of the bone.

For example, the document US-2011/009.866 describes a system forosteotomy composed of a plate which includes two ends aligned along alongitudinal axis fitting together through a median portion and screws.The first end includes a cutting edge and a hole which receives anon-interlocking screw and presents a chamfer which narrows from alesser thickness at the edge in the direction of the hole, the secondend has a locking hole which receives a safety screw, and the first andthe second hole are aligned along the longitudinal axis.

The drawback of this device is primarily the lack of stability: as amatter of fact, the configuration of this implant does not allow it tobe supported by the cortical of the proximal end of the calcaneum. Itsonly support therefore is the spongy bone which is porous. In view ofthe extremely strong forces being applied to this bone, in particularduring walks, this system is liable to enter into rotation or slide inthe spongy part of the proximal portion of the calcaneum which makes itvery unstable and presents major risks for the patient.

Also known are calcanean implants which have no compressive effects onthe orthopedic screws allowing their fixing, or for which the locking ofsaid screws is done with a metal-metal coupling which leads, over time,to a cold solder of the galvanic couple leading to toxic corrosion forthe patient and making the later removal of the screws impossible.

Furthermore, these implants present the drawback of requiringparticularly invasive surgery for their installation, forcing thepractitioner to make significant opening incisions over the entirelateral portion of the calcaneum.

BRIEF SUMMARY OF THE INVENTION

One aim of the present invention is to remedy the drawbacks cited aboveby providing an implant capable of perennating, i.e. stabilizing andstiffening, the system created by the translation of the calcaneum.

According to the invention, this aim has been achieved by a calcaneumtranslation plate or implant, comprised of two end portions, i.e. aproximal anchoring portion and a distal fixing portion oriented inopposing directions and arranged in spaced parallel planes, saidproximal and distal portions connecting to the third intermediateportion presenting a general square profile and featuring twoperpendicular bearing surfaces, the proximal anchoring portion extendingfrom one of these surfaces and perpendicular thereto, whereas the distalfixing portion extends in the prolongation of the other bearing surface.

According to another characteristic arrangement, the proximal anchoringportion is constituted by a blade with a narrowing profile in thedirection of its free end.

An advantageous implementation consists of providing said blade withanti-backoff teeth preventing the rotation of the implant after itsinstallation. Preferably these anti-backoff teeth are present on thelateral edges of the proximal anchoring portion.

According to a preferred implementation, the intermediate portionpresents a shoulder at its bearing surface at the proximal portion ofthe implant. After the installation of the plate, said shoulder abutsagainst the thin cortical of the proximal end of the calcaneum and thusprevents the plate from sliding into the spongy part of the bone.

According to a characteristic implementation of the invention, thedistal portion of the plate features at least one hole for the passageof at least one fastening screw.

The intermediate portion of the plate may present a concavity which canaccommodate one or several holes for the passage of one or severalfastening screws. Advantageously, the distal and intermediate portionseach have two screw holes, the axis of the holes in the intermediateportion being inclined relative to the axis of the screw holes of thedistal face. Preferably, said holes have a conical shape.

According to a preferred implementation, the distal portion of the platepresents some embossing on its face in contact with the bone.

Remarkably, the intermediate portion of said plate presentsreinforcement gussets on its lateral edges.

BRIEF DESCRIPTION OF THE DRAWINGS

The aims, characteristics and advantages mentioned above and still more,will become clearer in the detailed description below and the attacheddrawings in which:

FIG. 1 is a front view of the calcanean translation plate according tothe invention.

FIG. 2 is a rear view of FIG. 1.

FIG. 3 is a perspective view of the plate according to the invention.

FIG. 4 is a side view of the calcanean translation plate according tothe invention.

FIGS. 5 and 6 illustrate, as examples, different implementations of theplate according to the invention, constituting a part of a set ofimplants that may be presented to the practitioner.

FIG. 7 is a longitudinal section, at a larger scale, along the line 7-7of FIG. 1.

FIG. 8 is a perspective view of the hindfoot showing the calcaneumtranslation plate according to the invention in the position of use, thedistal and proximal portions of the calcaneum being shown intransparency.

FIG. 9 is a detailed front view and at a larger scale, showing thebearing surface of the shoulder of the intermediate portion of the plateagainst the cortical of the proximal portion of the calcaneum.

Reference to said drawings is made to describe an interesting, althoughby no means limiting, example of implementation of the calcaneumtranslation plate according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The term “distal” designates the portion or end of a bone which is thefarthest away from the root of this bone. The term “proximal” designatesthe portion or end of a bone which is the closest to its fixing point.Here, the proximal end of the calcaneum is the one that is attached tothe ankle-bone and to the rest of the bones of the foot, the distalportion or end of the calcaneum designating the end of the bone whichosteotomy separates from the rest of the body. Likewise, the proximaland distal portions of the implant are defined depending on whethertheir bearing surface is the proximal or distal end of the calcaneum.

According to the invention, the objective has been achieved by animplant consisting of a plate 1 which is comprised of three parts: aproximal anchoring portion 2, a distal fixing portion 3 and anintermediate portion 4 which connects them. The distal and proximalportions 2 and 3 are oriented in opposing directions and positioned inspaced parallel planes P-P, P′-P′, and present a generally rectangularshape. The ergonomic design of the plates reduces friction with the skinas well as detection of the implant once it is installed.

The first proximal anchoring portion 2 is meant to insert itself in thespongy bone of the proximal end of the calcaneum, the second portion isa fixing face 3 and meant to place itself on the cortical surface of thedistal end of the calcaneum as its bearing surface, thus stabilizing theportion of the bone that has been separated from the rest of theskeleton by the osteotomy. Said distal and proximal portions 3 and 2 areattached to an intermediate portion 4 presenting a generally squareprofile and featuring two perpendicular bearing surfaces 5 and 6, theproximal anchoring portion extending from one of these surfaces 5 andperpendicularly to it, whereas the distal fixing portion extends in theprolongation of the other bearing surface 6.

The proximal and distal portions 2 and 3 are thus not aligned but setoff by said intermediate zone 4 which separates them.

Advantageously, the proximal anchoring portion of the plate according tothe invention may be constituted by a blade 7 presenting a narrowingprofile in the direction of its free end so as to form a cutting edge.

According to a characteristic arrangement of the invention the proximalanchoring portion 2 of the implant, i.e. the one meant to be inserted inthe spongy layer of the proximal end of the calcaneum, presentsanti-backoff teeth 8 which prevent the implant from dislodging itselfand stop it from rotating once it is inserted in the bone. Theseanti-backoff teeth are, for example, placed on the lateral edges of saidproximal portion 2.

According to a characteristic arrangement of the invention, theintermediate portion 4 of the plate has a concavity 9 on its bearingsurface 6 from which extends the distal fixing portion 3 of the placeand a shoulder 10 at its bearing surface 5 meant for the proximalanchoring portion 2 of the plate. In the position of use, the anchoringportion 2 being inserted in the spongy layer of the bone, said shoulder10 bears against the cortical layer of the proximal portion of thecalcaneum in order to stabilize the system and to prevent it fromslipping into this spongy part of the bone under the effect of theforces generated by the weight of the body.

According to a preferred implementation, the distal fixing portion 3 ofthe plate 1 presents an embossed area 11 to prevent the crushing anddamaging of the periosteum. The periosteum is the vascularized membranewhich covers the entire surface of the bones (with the exception of thearticular cartilage) and contains the blood vessels which carry thenutrients that are indispensable for their repair. Any damage to theperiosteum leads to the bone becoming incapable of regenerating itself,and even to its necrosis. This embossing 11 allows safeguarding theperiosteum by offering punctual bearing surfaces to the plate 1, and nota surface-wide load which compresses the periosteum and damages it, asis usually the case with calcanean implants.

According to one implementation of the invention, the distal fixingportion 3 of the plate features at least one hole 12 for the passage ofat least one fastening screw.

According to one example of implementation, the intermediate portionpresents a concavity 9 which may typically feature one or several holes13 for the passage of one or several fastening screws (15). Preferably,the distal portion 3 of the implant as well as the intermediate portion4 are both provided with holes 12 and 13 for the passage of the screws,the axis of the holes 13 of the intermediate portion being inclinedrelative to the axis of the holes 12 of the distal portion.

On the other hand, the translation plate of the calcaneum 1 according tothe invention does not have any holes in the end of the proximalanchoring portion 2.

According to the example illustrated in FIGS. 1 to 3, the distal 3 andintermediate 4 portions each present two holes for the passage of thescrews, said holes may present a conical shape. The large opening of theholes accessible from the inside of the plate constitutes the entranceof these, whereas the small opening of said holes opens on the outsideof the plate meant to be applied against the cortical of the distal endof the calcaneum as far as the distal face of the plate is concerned,and against the spongy portion of the proximal end of the calcaneum forthe concavity of the intermediate portion.

The calcanean translation plate 1 according to the invention consists ofa biocompatible, rigid but expansible material, to allow locking of thescrew heads while ensuring sufficient rigidity to fasten together thetwo portions of the bone created by the osteotomy.

For example, plate 1 is made of polyetheretherketone (PEEK), for exampleof the type commercialized under the registered brand name “PEEK-OPTIA”.

According to an advantageous implementation, the lateral walls of thehole passages 12 and 13 meant to receive the heads of orthopedic screws14 and 15 are expansible in the radial direction so as to permit thecompression of said screw heads which are inserted there, therebyensuring the locking or blocking of the screws in the calcaneantranslation plate and preventing any possibility of backward movementafter having been screwed into the bone material, which makes thetranslation resulting from the osteotomy operation permanent.

The screws 15 locking themselves in the holes 13 of the intermediateportion 4 do already have an angle of divergence which increases theholding force of the device and the maintenance in several planes. Thelocking action enables the screws 14 and 15 to become integral with theplate.

According to one implementation, the screws 15 which are seated in theproximal end of the calcaneum are already angled between 10° and 50°.According to an advantageous implementation, at least one of the screwsused with the plate according to the invention has a threaded head.

Advantageously, the biocompatible material constituting the implantcontains 30% carbon fibers which permits its future retrieval if needbe, while ensuring the necessary rigidity.

According to one implementation, the locking of the screw heads in PEEK(compression) is inspired by the patented system (FR-2.845.588“Selfblocking Device of osteosynthesis” in the name of BiotechInternational) and designated by the registered brand name “EASYLOCK”.

According to a characteristic example, the intermediate portion 4 ofplate 1 according to the invention presents reinforcing gussets 16 onits lateral edges.

According to an advantageous implementation of the invention, theportions of the plate that are not in contact with the bone, i.e. theintermediate portion 4 which has a square-shaped profile, the face ofthe distal portion of the plate which is not bearing against the bone aswell as the possibly present gussets 16, present rounded edges so as toincrease the contact surface and to reduce the angle of contact in orderto avoid any lesions caused by the friction coefficient between the skinand the translation plate.

In order to enable adaptation to the specific needs of the patient, eachcase being different, the implants according to the invention will bemade available to surgeons in the form of sets each consisting of aplurality of calcanean translation plates of different dimensions (forexample FIGS. 4, 5, and 6).

The calcanean translation plate according to the invention offersseveral interesting advantages and in particular:

-   -   Very great stability;    -   No space requirement for screw heads outside of the plate;    -   Anatomical conformance of the plate which adapts to the shape of        the bone;    -   Very good resistance to the weight of walking.

1-12. (canceled)
 13. A calcaneum translation plate, comprising: an intermediate portion having a first bearing surface and a second bearing surface, the first and second bearing surfaces being transverse; a proximal anchoring portion extending from the first bearing surface such that a portion of the first bearing surface extends away from the second bearing surface and past a connection of the proximal anchoring portion to the first bearing surface to form a shoulder; and a distal fixing portion extending as a prolongation of the second bearing surface.
 14. The calcaneum translation plate of claim 13, wherein the proximal anchoring portion is arranged in a proximal plane and the distal fixing portion is arranged in a distal plane, the proximal plane and the distal plane being spaced apart and parallel.
 15. The calcaneum translation plate of claim 13, wherein the distal fixing portion includes at least one hole for passage of at least one fastening screw.
 16. The calcaneum translation plate of claim 15, wherein said at least one hole has a conical shape.
 17. The calcaneum translation plate of claim 13, wherein the intermediate portion includes a concavity having at least one hole for passage of at least one fastening screw.
 18. The calcaneum translation plate of claim 13, wherein the distal fixing portion and the intermediate portion are both provided with holes for passage of screws, an axis of a hole of the intermediate portion being inclined relative to an axis of a hole of the distal fixing portion.
 19. The calcaneum translation plate of claim 13, wherein the intermediate portion includes, on its lateral edges, reinforcing gussets.
 20. The calcaneum translation plate of claim 13, wherein the proximal anchoring portion includes anti-backoff teeth positioned on lateral edges of the proximal anchoring portion.
 21. The calcaneum translation plate of claim 13, wherein the proximal anchoring portion comprises a blade presenting a narrowing profile in a direction of its free end.
 22. A calcaneum translation plate, comprising: an intermediate portion having a first bearing surface and a second bearing surface, the first and second bearing surfaces being transverse; a proximal anchoring portion extending from the first bearing surface, wherein the proximal anchoring portion comprises a blade presenting a narrowing profile in a direction of its free end; and a distal fixing portion extending as a prolongation of the second bearing surface.
 23. The calcaneum translation plate of claim 22, wherein the proximal anchoring portion is arranged in a proximal plane and the distal fixing portion is arranged in a distal plane, the proximal plane and the distal plane being spaced apart and parallel.
 24. The calcaneum translation plate of claim 22, wherein the distal fixing portion includes at least one hole for passage of at least one fastening screw.
 25. The calcaneum translation plate of claim 24, wherein said at least one hole has a conical shape.
 26. The calcaneum translation plate of claim 22, wherein the intermediate portion includes a concavity having at least one hole for passage of at least one fastening screw.
 27. The calcaneum translation plate of claim 22, wherein the distal fixing portion and the intermediate portion are both provided with holes for passage of screws, an axis of a hole of the intermediate portion being inclined relative to an axis of a hole of the distal fixing portion.
 28. The calcaneum translation plate of claim 22, wherein the intermediate portion includes, on its lateral edges, reinforcing gussets.
 29. The calcaneum translation plate of claim 22, wherein the proximal anchoring portion includes anti-backoff teeth positioned on lateral edges of the proximal anchoring portion.
 30. A calcaneum translation plate, comprising: an intermediate portion having a first bearing surface and a second bearing surface, the first and second bearing surfaces being transverse, the intermediate portion including a concavity having at least one hole for passage of at least one fastening screw; a proximal anchoring portion extending from the first bearing surface; and a distal fixing portion extending as a prolongation of the second bearing surface, the distal fixing portion having at least one hole for passage of at least one fastening screw; wherein an axis of the at least one hole of the intermediate portion is inclined relative to an axis of the at least one hole of the distal fixing portion.
 31. The calcaneum translation plate of claim 30, wherein the proximal anchoring portion is arranged in a proximal plane and the distal fixing portion is arranged in a distal plane, the proximal plane and the distal plane being spaced apart and parallel.
 32. The calcaneum translation plate of claim 30, wherein the proximal anchoring portion includes anti-backoff teeth positioned on lateral edges of the proximal anchoring portion. 